Concentration of ores by flotation



Patented Oct. 28, 1930 UNITED STATES PATENT OFFICE ELMEB KEISEB BOLTON,.OF WILMINGTON, DELAWARE, ASSIGNOB. '10 E. I. DU PONT NEMIOURS 86COMPANY, OF WILMINGTON, DELAWARE, A CORPORATION OF DELA- WARE.

Ho Drawing.

This invention relates to the concentration of ores, minerals and thelike by flotation, and involves the use of a new class of flotationagents. One object of my invention is to improve on flotation processesby providing certain highly eflicient flotation agents. Other objectswill be apparent from the following descri tion.

I ave discovered that excellent results may be obtained inthe recoveryof ore values by flotation if there is used in the flotation process asubstance belonging to the class of compounds knownas'mercapto-thia'zoles, or the salts or oxidation products of suchthiazoles. For example, recoveries of ore values, with high yields, havebeen obtained using as flotation. agents such aromaticmercapto-thiazoles as mercapto-benzothiazole, l-mercapto-3-methyl-benzo-thiazole, and mercapto-alpha naphthyl-thiazole. Andinstead of a mercapto-thiazole, a salt thereof may be used, as forexample the sodium salt, or the zinc salt.

I have found that this class of compounds is unusually eificient andselective when used in the flotation of sulphide minerals. In someinstances an exce tionally high recovery, accompanied by a igh ratio ofconcentration, can be obtained. In other cases the ratio ofconcentration is unusually high, yet the recovery is 'very good. Theamount of reagent required is small; in some cases satisfactory resultsare obtained using the reagent in the proportion of .02 lb. per ton ofdry ore. v

The following examples give typical flotation results obtainable in thepractice of the present invention.

Example I I 350 cc. of water, 500 g. of ore from the Utah Copper Co.,and 2.2 g.of lime. (suflicient lime used to give a slightly alkalinetailing) ound in jar mill and then transferred to'the anney flotationmachine. During the trans- CONCENTBATIQN DRES IY FLOIATION Applicationfiled November 80, 1925. Serial No. 72,147.

fer 450 cc. of water is used, making a total of 800 cc. present. Thepulp is pre-agitated min., and agitation is then stopped while .04 gramsof pine oil and .025 grams of mercaptoenzo-thiazole are added. Thesereagents are pre-agitated with the ore pulp for 1 -min., and then 1200co. more water is added which allows circulation of pulp and results infroth formation. This procedure gave a 0.16% copper tailing recoverybeing 86.2%.

When the above procedure was carried out with .02 lb. ofmercapto-benzo-thiazole (instead-of 0.10 lb.) per ton of dry ore a-0.21%copper tailing and a 12.5% copper rougher concentrate resulted.

Froth is removed for 7 min.

, and a 12% copper rougher concentrate, the

When potassium ethyl xanthate' is used in Example [I Tests were made onore from the Inspiration Consolidated Copper Co. according to thefollowing general procedure. 750 cc. water, 750 g. ore and 0.7 g. limeground in a jar'mill for 20 min. and then transferred to a square glassjar with the addition of 1250 cc. water making a total of 2000 cc. ofwater. This pulp is pro-agitated with .04 g.

pine oil and .034 g. of mercapto-benzothiazole for l 'min. and thentransferred to the Callow cell containing 400 cc. of water. Froth isslowly overflowed for 10 min. This gave a 0.25% copper tailing with a20% copper rougher concentrate giving a recoveny of 7 5.3%.

Example 111 Following the same procedure as in Example II, except that(1) .02 lb. of mercapto-benzo-thiazole per ton of dry ore was usedinstead of .09 lb. and (2) 2.9 lb. of lime was used instead of 1.9 1b.,a .30% copper tailing resulted and an 18.% copper rougher concentrate,showing a recovery of 70.2%, was obtained.

As a basis of comparison several tests have been carried out withpotassium ethyl xanthate using the same general procedure outlinedabove. In no case has a tailing been obtained which contained less than.27 :opper with an approximately 20% rougher concentrate. Both 0.10 and0.20 lbs. of potassium ethyl xanthate per ton of dry ore were used.

Edample IV gave a 0.36% copper tailing and a 25% cop per rougherconcentrate. This compares with a. .34% copper tailing and a 13% copperrougher concentrate obtained with 0.10 lb. of potassium ethyl xanthatewhen added direct to the Callow cell.

Ewample V Using Anaconda table tailings and employing .02 of a pound of1-mercapto-3-methylbenzo-thiazole per ton of ore a concentrate wasobtained which contained10.39% of copper and represented 94% recovery ofcopper from the ore. The tailings contained 0.13% copper.

The zinc salt of l-mercapto-3-methyl-. benzo-thiazole, when used inamounts of 0.02 pound per ton of copper concentrate, contained 12.32% ofcopper which'is equivalent to 80.5% and the tailings contained 0.42%copper.

\Vhen .02 pound of mercapto-naphthylthiazole per ton of ore were used, aconcentrate was obtained which contained 14.35% copper and wasequivalent to 89% recovery. The tailings contained 0.32% of copper.

When Utah Copper Company ore was employed and 031 of a pound per ton ofl-mercapto-3-methyl-benzo-thiazole was used, a concentrate containing11.2% of copper resulted, which is equivalent to 82.3% recovery. Thetailings contained 0.20% copper. When a sin ilar quantity of zinc saltwas used the concentrate contained 13.35% copper, which is equivalent toan 83.5% recovery; the tail ings also contained 0.20% copper.

The mercapto-benzo-thiazole used in Examples I, II, and III was preparedby heating thiocarbanilide and sulphur to a temperature of about 225250.C. in an autoclave in a manner similar to that described by Sebrell andBedford in their article on the preparation and properties ofl-mercaptobenzo-thiazole, its homologues and derivatives, which waspublished in Vol. 45, on page 2390 of the Journal of the AmericanChemical Society. The reaction mixture obtained from the autoclave wastreated with warm dilute sodium hydroxide, and this alkaline solutionwas submitted to steam distillation to remove any free aniline. Thesolution was then acidified fractionally and inthe latter fractions apure-merca to-benzo-thiazole was obtained. In some 0 our experiments thesodium salt of mercapto-benzosthiazole was used, and these solutionswere prepared either by solution of the mercapto-benzo-thiazole insodium hydroxide, or the original reaction mixture, after being freedfrom anilin by steam distillation, was filtered and used directly in theflotation tests.

l-mercapto-3-methyl-benzo-thiazole was prepared by heating equimolecularamounts of sulfur and di ortho-tolyl-thio-urea for four hours at 250 C.in an autoclave. The charge was then cooled and any residual pressurereleased. The reaction product was extracted with warm dilute causticsoda solution and then steam distilled to remove any ortho-toluidine.The solution of the sodium salt of 1-mercapto-3-methyl-benzo-thiazolewas then filtered and the free mercaptomethyl-benzo-thiazole isolated byacidification with hydrochloric acid. This crude product was purifiedbyre-solution in warm dilute caustic soda, filtration and reprecipitationwith h drochloric acid. The product was then fi tened, washed with waterand dried at C.

The mercapto-alpha-naphthyl-thiazole was prepared by heatingequimolecular amounts of alpha-naphthylamine, carbon disulphide andsulfur for four hours at 250 C. in an 1 autoclave. At the end of thistime the charge was cooled, the pressure released and the material wasextracted with warm dilute caustic sodasolution and then filtered. Themercapto-naphthyl-thiazole was precipitated by acidification withhydrochloric acid. The crude product was re-dissolved in dilute causticsoda solution, filtered and reprecipitated by means of hydrochloricacid. This product was filtered, washed and dried at 90 C.

Although my invention has been described with reference to certainspecific flotation agents, it will be understood that these 125 specificflotation agents are merely typical, and that my invention is notlimited thereto, but includes the use in ore flotations, and particularlin sulphide mineral flotations, of mercapto-tiiiazoles broadly, themolecules of we these merca to-thi'azoles containing the folprobably thefollowing structural formula:

o-sn V H The l-mercapto-alpha-naphtho-thiazole has probably thestructure shown in the following formula: j

The ore-flotations carried out in accordance with my invention normallyrequire a froth-produclng agent. In place of the pine oil for thispurpose mentioned in Example I, I may use other frothing' agents such ashard wood creosote or terpineol.

In Exam le I the ore pulp is made alkaline with lime, ut I may alsopractice my invention with ore pulp in a non-alkaline condition.

I claim:

1. In the process of concentrating ores and minerals by flotation, thestep which comprises subjectin the ore in the-form of a pulp to a frothotation operation in the presence of a mercapto-thiaz'ole.

2 In the process of concentrating ores and minerals by flotation, thestep which comprises subecting a sulphide ore in the form of a pulp to afroth flotation operation in the presence of a mercapto-thiazole.

3. Inthe process of concentratlng ores and minerals by flotation, thestep which comprises subjecting the ore in the form of a pulp to a frothflotation operation in the presence of a mercapto-benzo-thiazole.

4. In the process of concentrating ores and minerals by flotation, thestep which compr ses subjectin the ore in the form of a pulp to a frotflotation operation in the presence ofl-mercapto-3-methyl-benzothiazole.

5. In the process of concentrating ores and minerals by flotation, thestep which comprises subjecting the ore in the form of a pulp to a frothflotation operation in the presence of a sodium salt of amercaptothiazole.

presence of a metal salt of a mercapto-thiazole.

7 In the process of concentrating ores and 8. In the process ofconcentrating ores and minerals by flotation, the stepwhich comprisessubjecting the ore in the form of a pulp to a flotation operation in thepresence of a froth-producing agentmand in the presence of a flotationagent whose molecules contain the following atomic group- 9. A processof concentrating ores and minerals as set forth in claim 8 in which lessthan one-tenth of a pound of flotation agent is used per ton of dry ore.

10. In the process of concentrating ores and minerals by flotation, thestep which comprises subjecting the ore in the form of a pulp to a frothflotation operation in the presence of 1-mercapto-benzo-thiazole.

11. The process of. concentrating a complex ore, which includesagitating pulp of the ore with a mercapto thiazole and a frothing agentto form a mineral-bearing froth relatively rich in one of the mineralsand separating the froth so obtained.

12. The process of concentrating a complex ore, which includes agitatinga pulp of the ore with l-mercapto benzothiazole and a frothing agent toform a mineral-bearing froth relatively rich in one of the minerals andse arating the froth so obtained.

13. n the process of concentrating ores and minerals by flotation, thestep which comprises subjectin the ore in the form of.

a pulp to a froth otation operation in the presence of amercapto-naphtho-thiazole.

14. In the process of concentrating ores and minerals by flotation, thestep which comprises subjectin the ore in the form of a pulp. to a frothotation operation in the prlesence of 1-mercapto alpha-naphtho-thia- 20e.

In testimony whereof I afiix my si ature.

. ELMER K. BOL ON.

